/* eslint-disable */
const FileSaver = require('file-saver');
import XLSX from 'xlsx'

function generateArray(table) {
    var out = [];
    var rows = table.querySelectorAll('tr');
    var ranges = [];
    for (var R = 0; R < rows.length; ++R) {
        var outRow = [];
        var row = rows[R];
        var columns = row.querySelectorAll('td');
        for (var C = 0; C < columns.length; ++C) {
        var cell = columns[C];
        var colspan = cell.getAttribute('colspan');
        var rowspan = cell.getAttribute('rowspan');
        var cellValue = cell.innerText;
        if (cellValue !== "" && cellValue == +cellValue) cellValue = +cellValue;

        //Skip ranges
        ranges.forEach(function (range) {
            if (R >= range.s.r && R <= range.e.r && outRow.length >= range.s.c && outRow.length <= range.e.c) {
            for (var i = 0; i <= range.e.c - range.s.c; ++i) outRow.push(null);
            }
        });

        //Handle Row Span
        if (rowspan || colspan) {
            rowspan = rowspan || 1;
            colspan = colspan || 1;
            ranges.push({
            s: {
                r: R,
                c: outRow.length
            },
            e: {
                r: R + rowspan - 1,
                c: outRow.length + colspan - 1
            }
            });
        };

        //Handle Value
        outRow.push(cellValue !== "" ? cellValue : null);

        //Handle Colspan
        if (colspan)
            for (var k = 0; k < colspan - 1; ++k) outRow.push(null);
        }
        out.push(outRow);
    }
    return [out, ranges];
};

function datenum(v, date1904) {
    if (date1904) v += 1462;
    var epoch = Date.parse(v);
    return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000);
}

function sheet_from_array_of_arrays(data, opts) {
    var ws = {};
    var range = {
        s: {
        c: 10000000,
        r: 10000000
        },
        e: {
        c: 0,
        r: 0
        }
    };
    for (var R = 0; R != data.length; ++R) {
        for (var C = 0; C != data[R].length; ++C) {
        if (range.s.r > R) range.s.r = R;
        if (range.s.c > C) range.s.c = C;
        if (range.e.r < R) range.e.r = R;
        if (range.e.c < C) range.e.c = C;
        var cell = {
            v: data[R][C]
        };
        if (cell.v == null) continue;
        var cell_ref = XLSX.utils.encode_cell({
            c: C,
            r: R
        });

        if (typeof cell.v === 'number') cell.t = 'n';
        else if (typeof cell.v === 'boolean') cell.t = 'b';
        else if (cell.v instanceof Date) {
            cell.t = 'n';
            cell.z = XLSX.SSF._table[14];
            cell.v = datenum(cell.v);
        } else cell.t = 's';

        ws[cell_ref] = cell;
        }
    }
    if (range.s.c < 10000000) ws['!ref'] = XLSX.utils.encode_range(range);
    return ws;
}

function Workbook() {
    if (!(this instanceof Workbook)) return new Workbook();
    this.SheetNames = [];
    this.Sheets = {};
}

function s2ab(s) {
    var buf = new ArrayBuffer(s.length);
    var view = new Uint8Array(buf);
    for (var i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF;
    return buf;
}

function export_table_to_excel(id) {
    var theTable = document.getElementById(id);
    var oo = generateArray(theTable);
    var ranges = oo[1];

    /* original data */
    var data = oo[0];
    var ws_name = "SheetJS";

    var wb = new Workbook(),
        ws = sheet_from_array_of_arrays(data);

    /* add ranges to worksheet */
    // ws['!cols'] = ['apple', 'banan'];
    ws['!merges'] = ranges;

    /* add worksheet to workbook */
    wb.SheetNames.push(ws_name);
    wb.Sheets[ws_name] = ws;

    var wbout = XLSX.write(wb, {
        bookType: 'xlsx',
        bookSST: false,
        type: 'binary'
    });
    FileSaver.saveAs(new Blob([s2ab(wbout)], {
        type: "application/octet-stream"
    }), "test.xlsx")
}

function export_json_to_excel({
    header,
    data,
    filename,
    autoWidth = true,
    bookType=  'xlsx'
} = {}) {
    /* original data */
    filename = filename || 'excel-list'
    data = [...data]
    data.unshift(header);
    var ws_name = "SheetJS";
    var wb = new Workbook(),
        ws = sheet_from_array_of_arrays(data);

    if (autoWidth) {
        /*设置worksheet每列的最大宽度*/
        const colWidth = data.map(row => row.map(val => {
        /*先判断是否为null/undefined*/
        if (val == null) {
            return {
            'wch': 10
            };
        }
        /*再判断是否为中文*/
        else if (val.toString().charCodeAt(0) > 255) {
            return {
            'wch': val.toString().length * 2
            };
        } else {
            return {
            'wch': val.toString().length
            };
        }
        }))
        /*以第一行为初始值*/
        let result = colWidth[0];
        for (let i = 1; i < colWidth.length; i++) {
        for (let j = 0; j < colWidth[i].length; j++) {
            if (result[j]['wch'] < colWidth[i][j]['wch']) {
            result[j]['wch'] = colWidth[i][j]['wch'];
            }
        }
        }
        ws['!cols'] = result;
    }

    /* add worksheet to workbook */
    wb.SheetNames.push(ws_name);
    wb.Sheets[ws_name] = ws;

    var wbout = XLSX.write(wb, {
        bookType: bookType,
        bookSST: false,
        type: 'binary'
    });
    FileSaver.saveAs(new Blob([s2ab(wbout)], {
        type: "application/octet-stream"
    }), `${filename}.${bookType}`);
}
export default {export_json_to_excel}